Amberlite XAD Resins Impregnated with Ionic Liquids for Au(III) Recovery

Abstract : Phosphonium‐based ionic liquids have been successfully impregnated on several Amberlite XAD resins for recovering Au(III) chloro‐anions. Sorption performance was evaluated through sorption isotherms (very favorable profiles) and uptake kinetics (controlled by the resistance to intraparticle diffusion). The binding mechanism consists of an ion‐exchange between AuCl4− and the counter ion bound to the phosphonium cation. Increasing the IL loading proportionally increases the sorption capacity but decreases the sorption speed (by increasing the resistance to intraparticle diffusion). Changing the counter ion on the phosphonium cation (i.e., complex anion vs. chloride ion) does not improve sorption performance. Highly porous resin (high pore volume and large pore size), such as Amberlite XAD‐1180, shows the best diffusion performance and highest sorption velocity (lower equilibrium time).